Apparatus for forming discrete, shaped interlayer blanks comprises, in combination, an extrusion die containing a slot for forming a sheet from thermoplastic melt, means associated with the die for causing a portion of the melt to exit the slot at a greater mass flow rate than that of the remainder of the melt exiting the slot, means adjacent the die for quenching the sheet immediately after forming and frusto-conical pull rolls for forwardly shaping the sheet into arcuate form, the surfaces of said rolls adjacent the edges of greatest circumference positioned to contact the portion of the sheet formed from the melt exiting the slot at the greater mass flow rate.